Photoacoustic image generation apparatus and insert

ABSTRACT

A puncture needle is at least partially inserted into a subject. An optical fiber guides light with a first wavelength and an optical fiber guides light with a second wavelength. The light guided by the optical fiber is emitted from a first light emitting portion and the light guided by the optical fiber is emitted from a second light emitting portion. A light absorption member absorbs the light with the first wavelength emitted from the first light emitting portion to generate photoacoustic waves and transmits the light with the second wavelength emitted from the second light emitting portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of InternationalApplication No. PCT/JP2016/003796 filed Aug. 22, 2016, the disclosure ofwhich is incorporated herein by reference in its entirety. Further, thisapplication claims priority from Japanese Patent Application No.2015-170512, filed Aug. 31, 2015, the disclosure of which isincorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to a photoacoustic image generationapparatus, and more particularly, to a photoacoustic image generationapparatus that detects photoacoustic waves generated by the absorptionof light by a light absorber and generates a photoacoustic image.

In addition, the invention relates to an insert such as a punctureneedle used in the photoacoustic image generation apparatus.

2. Description of the Related Art

An ultrasonography method has been known as a kind of image inspectionmethod that can non-invasively inspect the internal state of a livingbody. In ultrasonography, an ultrasound probe that can transmit andreceive ultrasonic waves is used. In a case in which the ultrasoundprobe transmits ultrasonic waves to a subject (living body), theultrasonic waves travel in the living body and are reflected from theinterface between tissues. The ultrasound probe receives the reflectedultrasonic waves and a distance is calculated on the basis of the timeuntil the reflected ultrasonic waves return to the ultrasound probe. Inthis way, it is possible to capture an image indicating the internalaspect of the living body.

In addition, photoacoustic imaging has been known which captures theimage of the inside of a living body using a photoacoustic effect. Ingeneral, in the photoacoustic imaging, the inside of the living body isirradiated with pulsed laser light. In the inside of the living body, aliving body tissue absorbs the energy of the pulsed laser light andultrasonic waves (photoacoustic waves) are generated by adiabaticexpansion caused by the energy. For example, an ultrasound probe detectsthe photoacoustic waves and a photoacoustic image is formed on the basisof a detection signal. In this way, it is possible to visualize theinside of the living body on the basis of the photoacoustic waves.

For the photoacoustic imaging, JP2015-37519A discloses a technique inwhich light emitted from a light source is guided to the vicinity of aleading end of a puncture needle by, for example, an optical fiber andis emitted from the leading end to a photoacoustic wave generationportion of the puncture needle. The photoacoustic wave generationportion includes, for example, a light absorption member. JP2015-37519Adiscloses a technique in which the light absorption member can be madeof, for example, an epoxy resin, a polyurethane resin, or a fluorineresin with which a black pigment is mixed, silicon rubber, or a blackpaint having high light absorbance with respect to the wavelength oflaser light. In addition, JP2015-37519A discloses a technique in which ametal film or an oxide film having light absorptivity with respect tothe wavelength of laser light is used as the light absorption member. Anultrasound probe detects the photoacoustic waves generated by theemission of light to the photoacoustic wave generation portion and aphotoacoustic image is generated on the basis of a detection signal ofthe photoacoustic waves. In the photoacoustic image, a part of thephotoacoustic wave generation portion appears as a bright point, whichmakes it possible to check the position of the puncture needle using thephotoacoustic image.

Furthermore, JP2013-13713A discloses a puncture needle including a lightemitting portion. In JP2013-13713A, light emitted from a light source isguided to the light emitting portion of the puncture needle by, forexample, an optical fiber and is emitted from the light emitting portionto the outside. In a subject, photoacoustic waves are generated due tothe absorption of the light emitted from the light emitting portion. Anultrasound probe detects the photoacoustic waves generated by theabsorption of the light emitted from the light emitting portion of thepuncture needle and a photoacoustic image is generated on the basis ofthe detection signal of the photoacoustic waves. In this way, it ispossible to check the position of the puncture needle.

In JP2015-37519A, the light absorber provided at the leading end of theneedle generates photoacoustic waves and the light absorber absorbsalmost all of the light emitted to the photoacoustic wave generationportion. Therefore, even in a situation in which the light absorber ispresent in front of the needle in a needling direction in the subject,it is difficult for the light absorber to generate photoacoustic waves.For this reason, in JP2015-37519A, only the positional information ofthe tip of the needle can be acquired and it is difficult to acquiresurrounding environment information such as information indicatingwhether the light absorber is present in the vicinity of the needle. Incontrast, in JP2013-13713A, the light absorber that is present in frontof the needle in the needling direction in the subject is irradiatedwith the light emitted from the light emitting portion. Therefore, in acase in which light with a wavelength absorbed by blood (blood vessel)is emitted from the light emitting portion, it is possible to determinewhether the tip of the needle has been inserted into the blood vessel onthe basis of whether a bright point is present in the photoacousticimage. However, in JP2013-13713A, the light emitting portion is exposedfrom, for example, a leading end portion of the needle and it isnecessary to cover the leading end of the light emitting portion with anappropriate member.

In JP2013-13713A, the photoacoustic waves generated by the absorption ofthe light emitted from the light emitting portion by, for example, metalforming a puncture needle main body are detected in addition to thephotoacoustic waves generated by the absorption of the light emittedfrom the light emitting portion by the light absorber that is present infront of the needle in the needling direction in the subject. However,it is considered that the intensity of the photoacoustic waves generatedby the absorption of light by, for example, metal in JP2013-13713A islower than the intensity of the photoacoustic waves generated by theabsorption of light by the light absorber in JP2015-37519A. Therefore,it is considered that the positional information of the tip of theneedle acquired in JP2013-13713A is not clearer than the positionalinformation of the tip of the needle acquired in JP2015-37519A.

SUMMARY OF THE INVENTION

The invention has been made in view of the above-mentioned problems andan object of the invention is to provide a photoacoustic imagegeneration apparatus that can acquire both positional information andsurrounding environment information of an insert.

In addition, another object of the invention is to provide an insertthat can acquire both the positional information and the surroundingenvironment information of the insert.

In order to achieve the objects, the invention provides an insert thatis at least partially inserted into a subject. The insert includes: afirst light guide member that guides light with a first wavelength; afirst light emitting portion from which the light guided by the firstlight guide member is emitted; a second light guide member that guideslight with a second wavelength different from the first wavelength; asecond light emitting portion from which the light guided by the secondlight guide member is emitted; and a light absorption member that atleast partially covers both the first light emitting portion and thesecond light emitting portion, absorbs the light with the firstwavelength emitted from the first light emitting portion to generatephotoacoustic waves, and transmits the light with the second wavelengthemitted from the second light emitting portion.

In addition, the invention provides a photoacoustic image generationapparatus including: a first light source that emits light with a firstwavelength; a second light source that emits light with a secondwavelength different from the first wavelength; an insert that is atleast partially inserted into a subject and includes a first light guidemember which guides the light with the first wavelength, a first lightemitting portion from which the light guided by the first light guidemember is emitted, a second light guide member which guides the lightwith the second wavelength, a second light emitting portion from whichthe light guided by the second light guide member is emitted, and alight absorption member which at least partially covers both the firstlight emitting portion and the second light emitting portion, absorbsthe light with the first wavelength emitted from the first lightemitting portion to generate photoacoustic waves, and transmits thelight with the second wavelength emitted from the second light emittingportion; acoustic wave detection unit for detecting first photoacousticwaves which are generated by the absorption of the light with the firstwavelength by the light absorption member and second photoacoustic waveswhich are generated in the subject due to the light emitted from thesecond light emitting portion; and photoacoustic image generation unitfor generating a first photoacoustic image on the basis of the firstphotoacoustic waves, generating a second photoacoustic image on thebasis of the second photoacoustic waves, and generating a thirdphotoacoustic image on the basis of both the first photoacoustic wavesand the second photoacoustic waves.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a photoacoustic image generationapparatus according to a first embodiment of the invention.

FIG. 2 is a perspective view illustrating the vicinity of a leading endof a puncture needle.

FIG. 3 is a graph illustrating an example of an absorption spectrum of alight absorption member.

FIG. 4 is a cross-sectional view illustrating the vicinity of a leadingend of a puncture needle according to a modification example.

FIG. 5 is a flowchart illustrating the procedure of an operation of thephotoacoustic image generation apparatus.

FIG. 6 is a flowchart illustrating the procedure of a firstphotoacoustic image generation process.

FIG. 7 is a flowchart illustrating the procedure of a secondphotoacoustic image generation process.

FIG. 8 is a flowchart illustrating the procedure of a thirdphotoacoustic image generation process.

FIG. 9 is a flowchart illustrating the procedure of an ultrasound imagegeneration process.

FIG. 10 is a graph illustrating the absorbance-wavelengthcharacteristics of a phosphor.

FIG. 11 is a graph illustrating the emission intensity-wavelengthcharacteristics of the phosphor.

FIG. 12 is a cross-sectional view illustrating the vicinity of a leadingend of a puncture needle according to a third embodiment of theinvention.

FIG. 13 is a cross-sectional view illustrating the vicinity of a leadingend of a puncture needle according to a modification example.

FIG. 14 is a top view illustrating a puncture needle according toanother modification example.

FIG. 15 is a top view illustrating a puncture needle according to stillanother modification example.

FIG. 16 is a cross-sectional view illustrating a puncture needleaccording to yet another modification example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the invention will be described in detailwith reference to the drawings. FIG. 1 illustrates a photoacoustic imagegeneration apparatus according to a first embodiment of the invention. Aphotoacoustic image generation apparatus 10 includes a probe (ultrasoundprobe) 11, an ultrasound unit 12, a first light source (laser unit) 13,a second light source (laser unit) 14, and a puncture needle 15. In theembodiment of the invention, ultrasonic waves are used as acousticwaves. However, the invention is not limited to the ultrasonic waves.Acoustic waves with an audible frequency may be used as long as anappropriate frequency can be selected according to, for example, aninspection target or measurement conditions.

The first light source 13 emits light with a first wavelength. Thesecond light source 14 emits light with a second wavelength. Forexample, the first light source 13 and the second light source 14 emitpulsed light with a pulse energy of about 0.3 μJ to 30 μJ and a pulsetime width of about 1 ns to 100 ns. The first wavelength and the secondwavelength are different from each other. The first light source 13 andthe second light source 14 are, for example, solid-state laser lightsources. The type of light source is not particularly limited. The firstlight source 13 and the second light source 14 may be laser diode lightsources (semiconductor laser light sources) or light amplifying laserlight sources having a laser diode light source as a seed light source.In addition, light sources other than the laser light source may beused.

The light with the first wavelength emitted from the first light source13 is guided to the puncture needle 15 by light guide means, such as anoptical fiber 17, and a light guide member (first light guide member),such as an optical fiber 153. The light with the second wavelengthemitted from the second light source 14 is guided to the puncture needle15 by light guide means, such as an optical fiber 18, and a light guidemember (second light guide member), such as an optical fiber 154.

The puncture needle 15 is a needle that is inserted into a subject. Theoptical fiber 153 and the optical fiber 154 are inserted into thepuncture needle 15. An optical connector 19 is provided between theoptical fiber 17 close to the first light source 13 and the opticalfiber 153 inserted into the puncture needle 15. The optical connector 19detachably connects the optical fiber 17 and the optical fiber 153.Similarly, an optical connector 20 is provided between the optical fiber18 close to the second light source 14 and the optical fiber 154inserted into the puncture needle 15. The optical connector 20detachably connects the optical fiber 18 and the optical fiber 154. Theconnection of the optical connector 19 and the optical connector 20 isreleased to throw away the optical fiber 153 and optical fiber 154together with the puncture needle 15 at the same time.

FIG. 2 illustrates the vicinity of a leading end of the puncture needle15. The puncture needle 15 has a light absorption member 51 provided inthe vicinity of the leading end. A leading end (a far end as viewed fromthe light source side) of the optical fiber 153 forms a light emittingportion (first light emitting portion) 153 a from which guided light isemitted. A leading end of the optical fiber 154 forms a light emittingportion (second light emitting portion) 154 a from which guided light isemitted. For example, the light absorption member 51 at least partiallycovers the first light emitting portion 153 a and the second lightemitting portion 154 a. The light absorption member 51 may also functionas a fixing member that fixes the optical fiber 153 and the opticalfiber 154 to the inner wall of an inner cavity of the puncture needle15. The optical fiber 153 and the optical fiber 154 may be coated. Forexample, polyimide, a fluorine resin, or an acrylic resin may be usedfor coating.

The light absorption member 51 absorbs the light with the firstwavelength emitted from the first light emitting portion 153 a andgenerates photoacoustic waves. The light absorption member 51 isprovided in the vicinity of the leading end of the puncture needle 15and can generate photoacoustic waves at a point in the vicinity of theleading end of the puncture needle 15. Since the length of a generationsource (sound source) of the photoacoustic waves is sufficiently smallerthan the total length of the puncture needle, the sound source can beregarded as a point sound source. In addition, the light absorptionmember 51 does not absorb the light with the second wavelength emittedfrom the second light emitting portion 154 a and transmits the lightwith the second wavelength to the outside of an opening portion providedat the leading end of the puncture needle 15. Even in a case in whichthe light with the second wavelength is emitted from the second lightemitting portion 154 a, the light absorption member 51 does not generatephotoacoustic waves since the light absorption member 51 does not absorbthe light with the second wavelength.

The first light emitting portion 153 a is provided in the vicinity ofthe leading end of the puncture needle 15. The optical fiber 153 guidesthe light with the first wavelength which is incident from the firstlight source 13 to the vicinity of the leading end of the punctureneedle 15. The second light emitting portion 154 a is also provided inthe vicinity of the leading end of the puncture needle 15 and theoptical fiber 154 guides the light with the second wavelength which isincident from the second light source 14 to the vicinity of the leadingend of the puncture needle 15. Here, “the vicinity of the leading end”means a position where the light absorption member 51 provided at theleading end can generate photoacoustic waves capable of imaging theposition of the leading end of the puncture needle 15 with accuracyrequired for a needling operation in a case in which the light emittingportion 153 a and the light emitting portion 154 a are disposed at theposition. For example, the vicinity of the leading end is the range of 0mm to 3 mm from the leading end to the base end of the puncture needle15.

In a case in which the light absorption member 51 transmits the lightwith the second wavelength, the light absorption member 51 does not needto transmit all of the light with the second wavelength. That is, thelight absorbance of the light absorption member 51 does not need to be0%. The light absorption member 51 may absorb and transmit the lightwith the second wavelength at a ratio of, for example, about 1:9.Similarly, in a case in which the light absorption member 51 absorbs thelight with the first wavelength, the light absorption member 51 does notneed to absorb all of the light with the first wavelength. That is, thelight absorbance of the light absorption member 51 does not need to be100%. The light absorption member 51 may absorb and transmit the lightwith the first wavelength at a ratio of, for example, about 9:1. Thesame description holds for the transmission of the light with the secondwavelength and the absorption of the light with the first wavelength orlight with a third wavelength which will be described below.

The light absorption member 51 includes, for example, a light absorberthat absorbs the light with the first wavelength and transmits the lightwith the second wavelength and a resin (for example, an epoxy resin)including the light absorber. For example, in a case in which a pulsedlaser diode with a wavelength of 905 nm is used as the first lightsource 13, a material that absorbs light with the wavelength is mixed asthe light absorber with a resin. For example, the following material canbe used as the light absorber: YKR-2900 or YKR-2081 which is aphthalocyanine-based material manufactured by Yamamoto Chemical IndustryCo., Ltd.; FDN-004 or FDN-005 manufactured by Yamada Chemical Co., Ltd.;a cyanine-based absorber material disclosed in JP5243056B; IRA908,IRA912, or IRA931 manufactured by Exciton Inc.; or S0433 manufactured byFEW Chemicals GmbH. In a case in which these absorbers are used, apulsed laser diode with a wavelength of 870 nm may be used as the firstlight source 13.

In a case in which a resin including the above-mentioned absorber isused as the light absorption member 51, light with a wavelength of 905nm emitted from the first light source 13 is converted into acousticwaves. The acoustic waves can be used to detect the position of theleading end of the puncture needle 15. In contrast, light emitted fromthe second light source 14 is transmitted through the light absorptionmember 51 and is emitted to the outside of the puncture needle 15. Thelight can be used to evaluate the surrounding environment of the leadingend portion of the puncture needle 15. The wavelength of the lightemitted from the second light source 14 can be appropriately selectedfrom a wavelength range in which absorbance is high in theabsorbance-wavelength characteristics of the absorber.

FIG. 3 illustrates an example of the absorption spectrum of the lightabsorption member 51. The horizontal axis indicates a wavelength and thevertical axis indicates absorbance. A cyanine-based absorber material isused as the absorber included in the light absorption member 51. In thelight absorption member 51, the absorbance of light with a wavelength ofabout 905 nm is the highest and the absorbance of light is rapidlyreduced toward a long wavelength side and a short wavelength side. In acase in which the light absorption member 51 is used, the wavelength ofthe light emitted from the second light source 14 may be appropriatelyselected from the range of 400 nm to 650 nm or the range of 1000 nm ormore.

The second wavelength is set according to materials around the part intowhich the puncture needle 15 is inserted. In other words, the secondwavelength is set according to an evaluation target material in thesurrounding environment of the puncture needle 15. A light sourceemitting light with a wavelength which is absorbed by an evaluationtarget material to generate photoacoustic waves is used as the secondlight source. For example, in a case in which the evaluation target isblood (blood vessel), a light source that emits light with a wavelengthof 530 nm is used as the second light source 14. In a case in which theevaluation target is a nerve, a light source that emits light with awavelength of 1210 nm is used as the second light source 14.

In a case in which the evaluation target is a contrast agent used tovisualize, for example, a lymph node or a lymph tube, a light sourceemitting light with a wavelength which is absorbed by the contrast agentto generate photoacoustic waves may be used as the second light source14. For example, in a case in which indocyanine green (ICG) is used asthe contrast agent, a light source that emits light with a wavelength of780 nm may be used as the second light source 14. In a case in whichmethylene blue is used as the contrast agent, a light source that emitslight with a wavelength of 663 nm may be used. In a case in which PatentBlue V is used as the contrast agent, a light source that emits lightwith a wavelength of 638 nm may be used.

In a case in which a specific material is transferred to, for example, acancer cell by a drug delivery system (DDS) and it is evaluated whetherthe material is present, a light source emitting light with a wavelengthwhich is absorbed by the material to generate photoacoustic waves may beused as the second light source 14. For example, in a case in which theevaluation target is a gold nanoparticle, a light source that emitslight in the wavelength range of 600 nm to 900 nm according to thediameter of the gold nanoparticle may be used as the second light source14. In a case in which the evaluation target is a carbon nanotube, alight source that emits light in the wavelength range of 670 nm to 820nm may be used as the second light source 14.

The first light source 13 is not limited to the light source that emitsonly the light with the first wavelength. A light source that can emitlight components with a plurality of wavelengths may be used as thefirst light source 13 and may emit light components with wavelengthsdifferent from the light with the first wavelength. An example of thelight source that can emit light components with a plurality ofwavelengths including the first wavelength (905 nm) is a Ti:Sf laser ora Nd:YAG-optical parametric oscillation (OPO) laser.

In addition, the second light source 14 is not limited to the lightsource that emits only the light with the second wavelength. The secondlight source 14 does not need to be only one light source and the secondlight source 14 may have two or more light sources. In this case, forexample, a wavelength division multiplexing coupler that multiplexeslight components with a plurality of wavelengths emitted from aplurality of light sources may be provided on an optical path throughwhich light emitted from the second light source 14 is incident on theoptical fiber 154. For example, the photoacoustic image generationapparatus 10 may include, as the second light source 14, a light sourcethat emits light with a wavelength of 530 nm and a light source thatemits light with a wavelength of 1210 nm. In this case, the user mayselect which of the light sources in the second light source 14 is to beused to emit light according to the evaluation target. Specifically, ina case in which the evaluation target is blood (blood vessel), a lightsource that emits light with a wavelength of 530 nm may be selected toemit light. In a case in which the evaluation target is a nerve, a lightsource that emits light with a wavelength of 1210 nm may be selected toemit light. For example, a menu for selecting an evaluation target maybe provided on a menu screen such that the user can select the lightsource to be used to emit light.

In a case in which the second light source 14 includes two or more lightsources, two or more light sources may be controlled such that they emitlight in time series while being switched. In this case, each lightsource may emit light, photoacoustic waves (second photoacoustic waves)may be detected, and second photoacoustic images corresponding to lightcomponents with each wavelength may be generated. In this case, thesecond photoacoustic images corresponding to light components with eachwavelength are displayed while being switched or are displayed side byside such that a plurality of types of evaluation targets can beevaluated.

The second light source 14 does not necessarily include light sourcesthat emit light with a plurality of single wavelengths and may be alight source that can emit light components with a plurality ofwavelengths while switching the light components. For example, OPO maybe used for the second light source 14. The OPO may be performed in abroad band and light with an arbitrary wavelength may be dispersed inthe broad band to select a wavelength. In addition, the second lightsource 14 may emit light components with a plurality of wavelengthsdifferent from the first wavelength while switching the light componentsand photoacoustic waves corresponding to the light components may bedetected. Then, the relationship between the wavelength and theintensity of the detected photoacoustic waves may be calculated toevaluate a surrounding environment. The surrounding environment may beevaluated to evaluate melanin (metastatic malignant melanoma), tomonitor a cauterized state, to monitor tissue death caused by ethanolinfusion, to detect nerve peaks, to evaluate the behavior of artheromaplaque, to evaluate liver fibrosis (scattering), and to evaluate thedegree of progress of inflammation.

The puncture needle 15 may further include a transparent resin thattransmits at least the light with the second wavelength. FIG. 4 is across-sectional view illustrating the leading end portion of thepuncture needle 15 including the transparent resin. In FIG. 4, theoptical fiber 154 which is a second light guide member is notillustrated. A transparent resin 52 transmits at least the light withthe second wavelength. The transparent resin 52 may transmit most ofincident light with the second wavelength and does not need to transmitall of the incident light with the second wavelength. That is, thetransparent resin 52 does not need to transmit 100% of the light withthe second wavelength. For example, an epoxy resin (adhesive) is used asthe transparent resin 52. For example, a thermosetting resin, anultraviolet-curable resin, or a photocurable resin is used as thetransparent resin 52.

A puncture needle main body 151 forming a main body portion of thepuncture needle 15 has an inner cavity. The transparent resin 52 coversthe light absorption member 51 in the inner cavity of the punctureneedle main body 151. The transparent resin 52 may cover at least one ofthe optical fiber 153 or the optical fiber 154 (not illustrated) in theinner cavity of the puncture needle main body 151. The transparent resin52 may function as a fixing member that fixes the light absorptionmember 51, the optical fiber 153, and the optical fiber 154 to the innerwall of the puncture needle main body 151. In FIG. 4, the lightabsorption member 51 covers the light emitting portion 153 a of theoptical fiber 153 and (the leading end portion of) the optical fiber 153and the light absorption member 51 are fixed to the inner wall of thepuncture needle main body 151 by the transparent resin 52. The lightabsorption member 51 also covers the light emitting portion 154 a of theoptical fiber 154 (not illustrated) and the optical fiber 154 is alsofixed to the inner wall of the puncture needle main body 151 by thetransparent resin 52.

Returning to FIG. 1, the probe 11 includes, for example, a plurality ofdetector elements (ultrasound transducers) which are acoustic wavedetection means and are one-dimensionally arranged. After the punctureneedle 15 is inserted into the subject, the probe 11 detects thephotoacoustic waves (first photoacoustic waves) generated from the lightabsorption member 51 (see FIG. 2) and photoacoustic waves (secondphotoacoustic waves) generated in the subject due to light emitted fromthe second light emitting portion 154 a (see FIG. 2). The probe 11performs the transmission of acoustic waves (ultrasonic waves) to thesubject and the reception of the reflected acoustic waves (reflectedultrasonic waves) with respect to the transmitted ultrasonic waves, inaddition to the detection of the photoacoustic waves. The transmissionand reception of the sound waves may be performed at differentpositions. For example, ultrasonic waves may be transmitted from aposition different from the position of the probe 11 and the probe 11may receive the reflected ultrasonic waves with respect to thetransmitted ultrasonic waves. The probe 11 is not limited to a linearprobe and may be a convex probe or a sector probe.

The ultrasound unit 12 includes a receiving circuit 21, a receivingmemory 22, data demultiplexing means 23, photoacoustic image generationmeans 24, ultrasound image generation means 25, image output means 26, atransmission control circuit 27, and control means 28. The ultrasoundunit 12 forms a signal processing device. The ultrasound unit 12typically includes a processor, a memory, and a bus. A program relatedto the generation of a photoacoustic image is incorporated into theultrasound unit 12. The program is executed to implement the functionsof at least some of the components in the ultrasound unit 12.

The receiving circuit 21 receives a detection signal output from theprobe 11 and stores the received detection signal in the receivingmemory 22. The receiving circuit 21 typically includes a low noiseamplifier, a variable gain amplifier, a low-pass filter, and ananalog-to-digital convertor (AD convertor). The detection signal fromthe probe 11 is amplified by the low noise amplifier. The gain of thedetection signal is adjusted by the variable gain amplifier according toa depth and a high-frequency component of the detection signal is cut bythe low-pass filter. Then, the detection signal is converted into adigital signal by the AD convertor and is stored in the receiving memory22. The receiving circuit 21 includes, for example, one integratedcircuit (IC).

The probe 11 outputs a detection signal of the photoacoustic waves and adetection signal of the reflected ultrasonic waves. The AD-converteddetection signals (sampling data) of the photoacoustic waves and thereflected ultrasonic waves are stored in the receiving memory 22. Thedata demultiplexing means 23 reads out the sampling data of thedetection signal of the photoacoustic waves from the receiving memory 22and transmits the sampling data to the photoacoustic image generationmeans 24. In addition, the data demultiplexing means 23 reads out thesampling data of the reflected ultrasonic waves from the receivingmemory 22 and transmits the sampling data to the ultrasound imagegeneration means (reflected acoustic image generation means) 25.

The photoacoustic image generation means 24 generates a photoacousticimage on the basis of the detection signal of the photoacoustic wavesdetected by the probe 11. The generation of the photoacoustic imageincludes, for example, image reconfiguration, such as phasing addition,detection, and logarithmic conversion. The ultrasound image generationmeans 25 generates an ultrasound image (reflected acoustic image) on thebasis of the detection signal of the reflected ultrasonic waves detectedby the probe 11. The generation of the ultrasound image includes, forexample, image reconfiguration, such as phasing addition, detection, andlogarithmic conversion. The image output means 26 outputs thephotoacoustic image and the ultrasound image to image display means 16such as a display device.

The control means 28 controls each component in the ultrasound unit 12.For example, in a case in which a photoacoustic image is acquired, thecontrol means 28 transmits a trigger signal to the first light source 13or the second light source 14 such that the first light source 13 or thesecond light source 14 emits laser light. In addition, the control means28 transmits a sampling trigger signal to the receiving circuit 21 tocontrol, for example, the sampling start time of the photoacoustic waveswith the emission of the laser light.

In a case in which an ultrasound image is acquired, the control means 28transmits an ultrasound transmission trigger signal for instructing thetransmission of ultrasonic waves to the transmission control circuit 27.In a case in which the ultrasound transmission trigger signal isreceived, the transmission control circuit 27 directs the probe 11 totransmit ultrasonic waves. For example, the probe 11 performs scanningwhile shifting acoustic lines one by one to detect reflected ultrasonicwaves. The control means 28 transmits a sampling trigger signal to thereceiving circuit 21 in synchronization with the transmission of theultrasonic waves to start the sampling of the reflected ultrasonicwaves.

The control means 28 may switch the operation mode of the photoacousticimage generation apparatus 10 among four operation modes. In a firstoperation mode, the first light source 13 emits light with the firstwavelength, the photoacoustic waves (first photoacoustic waves)generated from the light absorption member 51 are detected, and aphotoacoustic image (first photoacoustic image) is generated. In asecond operation mode, the second light source 14 emits light with thesecond wavelength, the photoacoustic waves (second photoacoustic waves)generated by the irradiation of the subject with the light with thesecond wavelength transmitted through the light absorption member 51 aredetected, and a photoacoustic image (second photoacoustic image) isgenerated. In a third operation mode, the first light source 13 emitslight with the first wavelength, the second light source 14 emits lightwith the second wavelength, both the photoacoustic waves (firstphotoacoustic waves) generated from the light absorption member 51 andthe photoacoustic waves (second photoacoustic waves) generated by theirradiation of the subject with the light with the second wavelengthtransmitted through the light absorption member 51 are detected, and aphotoacoustic image (third photoacoustic image) is generated. In afourth operation mode, ultrasonic waves are transmitted to the subject,ultrasonic waves reflected from the subject are detected, and anultrasound image is generated. A user, such as a doctor, can select theoperation mode using input means (not illustrated), such as a keyboardor a console switch. Alternatively, arbitrary operation modes among thefour operation modes may be sequentially automatically switched andimages obtained in each operation mode may be combined and displayed.

Next, the procedure of an operation will be described. FIG. 5illustrates the procedure of the operation of the photoacoustic imagegeneration apparatus 10. The operation mode selected by the user isstored in a variable mode. The control means 28 switches a processaccording to the variable mode (Step S1). In a case in which thevariable mode is the first operation mode, the control means 28 performsa first photoacoustic image generation process in the photoacousticimage generation apparatus 10 (Step S2). In a case in which the variablemode is the second operation mode, the control means 28 performs asecond photoacoustic image generation process in the photoacoustic imagegeneration apparatus 10 (Step S3). In a case in which the variable modeis the third operation mode, the control means 28 performs a thirdphotoacoustic image generation process in the photoacoustic imagegeneration apparatus 10 (Step S4). In a case in which the variable modeis the fourth operation mode, the control means 28 performs anultrasound image generation process in the photoacoustic imagegeneration apparatus 10 (Step S5). The photoacoustic image generationapparatus 10 displays the image generated in Step S2, Step S3, Step S4,or Step S5 on the image display means 16 (Step S6).

FIG. 6 illustrates the procedure of the first photoacoustic imagegeneration process. The control means 28 directs the first light source13 to emit light (Step S21). In Step S21, the control means 28 transmitsa trigger signal to the first light source 13. In a case in which thefirst light source 13 is a solid-state laser device including a flashlamp and a Q-switch, the trigger signal includes, for example, a flashlamp trigger signal and a Q-switch trigger signal. In the first lightsource 13, the flash lamp is turned on in response to the flash lamptrigger signal and then the Q-switch is driven in response to theQ-switch trigger signal to emit pulsed laser light with the firstwavelength. In a case in which the first light source 13 is a laserdiode, a laser driver circuit makes a predetermined amount of currentflow to the laser diode for the time corresponding to a pulse width inresponse to the trigger signal to emit pulsed laser light with the firstwavelength.

The pulsed laser light emitted from the first light source 13 isincident on the optical fiber 153 through the optical fiber 17 and theoptical connector 19, is guided to the vicinity of the leading end ofthe puncture needle 15 by the optical fiber 153, and is emitted from thefirst light emitting portion 153 a (see FIG. 2). At least a portion ofthe pulsed laser light is emitted to the light absorption member 51provided at the leading end of the puncture needle 15. The lightabsorption member 51 absorbs the light with the first wavelength andgenerates photoacoustic waves (Step S22).

The probe 11 detects the photoacoustic waves generated by the emissionof the laser light, that is, the photoacoustic waves (firstphotoacoustic waves) generated from the light absorption member 51 (StepS23). The photoacoustic waves detected by the probe are received by thereceiving circuit 21 and the sampling data of the photoacoustic waves isstored in the receiving memory 22. The photoacoustic image generationmeans 24 receives the sampling data of the detection signal of thephotoacoustic waves through the data demultiplexing means 23 andgenerates a photoacoustic image (first photoacoustic image) (Step S24).The photoacoustic image generation means 24 may apply a color map (StepS25) to convert the signal intensity of the photoacoustic image into acolor. The photoacoustic image generated by the photoacoustic imagegeneration means 24 is stored in, for example, an image memory (notillustrated) of the image output means 26 (Step S26).

FIG. 7 illustrates the procedure of the second photoacoustic imagegeneration process. The control means 28 directs the second light source14 to emit light (Step S31). In Step S31, the control means 28 transmitsa trigger signal to the second light source 14. In a case in which thesecond light source 14 is a solid-state laser device including a flashlamp and a Q-switch, the trigger signal includes, for example, a flashlamp trigger signal and a Q-switch trigger signal. In the second lightsource 14, the flash lamp is turned on in response to the flash lamptrigger signal and then the Q-switch is driven in response to theQ-switch trigger signal to emit pulsed laser light with the secondwavelength. In a case in which the second light source 14 is a laserdiode, a laser driver circuit makes a predetermined amount of currentflow to the laser diode for the time corresponding to a pulse width inresponse to the trigger signal to emit pulsed laser light with the firstwavelength.

The pulsed laser light emitted from the second light source 14 isincident on the optical fiber 154 through the optical fiber 18 and theoptical connector 20, is guided to the vicinity of the leading end ofthe puncture needle 15 by the optical fiber 154, and is emitted from thesecond light emitting portion 154 a (see FIG. 2). Since the lightabsorption member 51 covering the second light emitting portion 154 atransmits light with the second wavelength, the pulsed laser light withthe second wavelength emitted from the second light emitting portion 154a is emitted from the opening of the puncture needle 15 into thesubject. In a case in which an absorber that absorbs light with thesecond wavelength is present in the emission range of the pulsed laserlight with the second wavelength, photoacoustic waves (secondphotoacoustic waves) are generated from the absorber (Step S32).

The probe 11 detects the photoacoustic waves generated by the emissionof the laser light, that is, the photoacoustic waves (secondphotoacoustic waves) generated from the subject (Step S33). Thephotoacoustic waves detected by the probe are received by the receivingcircuit 21 and the sampling data of the photoacoustic waves is stored inthe receiving memory 22. The photoacoustic image generation means 24receives the sampling data of the detection signal of the photoacousticwaves through the data demultiplexing means 23 and generates aphotoacoustic image (second photoacoustic image) (Step S34). Thephotoacoustic image generation means 24 may apply a color map (Step S35)to convert the signal intensity of the photoacoustic image into a color.It is preferable that the color map used in Step S35 is different fromthe color map used to generate the first photoacoustic image. Thephotoacoustic image generated by the photoacoustic image generationmeans 24 is stored in, for example, the image memory (not illustrated)of the image output means 26 (Step S36).

FIG. 8 illustrates the procedure of the third photoacoustic imagegeneration process. The control means 28 directs the first light source13 and the second light source 14 to emit light (Step S41). The emissionof light from the first light source 13 by the control means 28 isperformed in the same procedure as that in Step S21 of FIG. 6. Theemission of light from the second light source 14 is performed in thesame procedure as that in Step S31 of FIG. 7.

The pulsed laser light emitted from the first light source 13 isincident on the optical fiber 153 through the optical fiber 17 and theoptical connector 19, is guided to the vicinity of the leading end ofthe puncture needle 15 by the optical fiber 153, and is emitted from thefirst light emitting portion 153 a (see FIG. 2). At least a portion ofthe pulsed laser light is emitted to the light absorption member 51provided at the leading end of the puncture needle 15. In addition, thepulsed laser light emitted from the second light source 14 is incidenton the optical fiber 154 through the optical fiber 18 and the opticalconnector 20, is guided to the vicinity of the leading end of thepuncture needle 15 by the optical fiber 154, is emitted from the secondlight emitting portion 154 a (see FIG. 2), passes through the lightabsorption member 51, and is emitted into the subject through theopening of the puncture needle 15. The light absorption member 51absorbs the light with the first wavelength and generates photoacousticwaves (first photoacoustic waves). The absorber that is present in theemission range of the pulsed laser light with the second wavelengthabsorbs light with the second wavelength and generates photoacousticwaves (second photoacoustic waves) (Step S42).

The probe 11 detects the photoacoustic waves generated by the emissionof the laser light, that is, the first photoacoustic waves generatedfrom the light absorption member 51 and the second photoacoustic wavesgenerated from the absorber in the subject (Step S43). The photoacousticwaves detected by the probe are received by the receiving circuit 21 andthe sampling data of the photoacoustic waves is stored in the receivingmemory 22. The photoacoustic image generation means 24 receives thesampling data of the detection signal of the photoacoustic waves throughthe data demultiplexing means 23 and generates a photoacoustic image(third photoacoustic image) (Step S44). The photoacoustic imagegeneration means 24 may apply a color map (Step S45) to convert thesignal intensity of the photoacoustic image into a color. Thephotoacoustic image generated by the photoacoustic image generationmeans 24 is stored in, for example, the image memory (not illustrated)of the image output means 26 (Step S46).

FIG. 9 illustrates the procedure of the ultrasound image generationprocess. The control means 28 transmits an ultrasound trigger signal tothe transmission control circuit 27. The transmission control circuit 27directs the probe 11 to transmit ultrasonic waves in response to theultrasound trigger signal (Step S51). The probe 11 transmits ultrasonicwaves and detects reflected ultrasonic waves (Step S52). The reflectedultrasonic waves detected by the probe 11 are received by the receivingcircuit 21 and the sampling data of the reflected ultrasonic waves isstored in the receiving memory 22. The ultrasound image generation means25 receives the sampling data of the detection signal of the reflectedultrasonic waves through the data demultiplexing means 23 and generatesan ultrasound image (Step S53). The ultrasound image generation means 25may apply a color map (Step S54) to convert the signal intensity of theultrasound image into a color. The ultrasound image generated by theultrasound image generation means 25 is stored in, for example, theimage memory (not illustrated) of the image output means 26 (Step S55).

The user can appropriately switch the operation mode among the first tofourth operation modes while inserting the puncture needle 15. Forexample, when starting the insertion of the puncture needle 15, the userselects the fourth operation mode and performs an operation such that anultrasound image is displayed on the image display means 16. Afterstarting the insertion, the user switches the operation mode to thefirst operation mode and performs an operation such that the firstphotoacoustic image is displayed on the image display means 16. In thefirst photoacoustic image, the position of the light absorption member51 that absorbs light with the first wavelength and generatesphotoacoustic waves appears as a bright point. Therefore, it is possibleto check the position of the leading end of the puncture needle 15 withreference to the first photoacoustic image.

In a case in which the puncture needle 15 is inserted to a certaindepth, the user switches the operation mode to the second operation modeand performs an operation such that the second photoacoustic image isdisplayed on the image display means 16. In a case in which a lightabsorber that absorbs light with the second wavelength is present in thevicinity of the leading end of the puncture needle 15 in the subject,the position of the light absorber appears as a bright point in thesecond photoacoustic image. For example, in a case in which the secondwavelength is a wavelength absorbed by blood and blood is present in thevicinity of the leading end of the puncture needle 15, a bright pointappears in the second photoacoustic image. The user can determinewhether the puncture needle 15 has been inserted to the part in whichblood is present, on the basis of whether a bright point is present. Thephotoacoustic image generation apparatus 10 may determine whether thesum of the signals of the second photoacoustic image is equal to orgreater than a threshold value. In a case in which the sum of thesignals is equal to or greater than the threshold value, thephotoacoustic image generation apparatus 10 may notify the user of thedetermination result. The user may perform a needling operation whilealternately switching the operation mode between the first operationmode and the second operation mode or after selecting the thirdoperation mode.

In the above description, the first photoacoustic image, the secondphotoacoustic image, the third photoacoustic image, and the ultrasoundimage are generated in the independent operation modes. However, theinvention is not limited thereto. For example, at least one of the firstphotoacoustic image, the second photoacoustic image, or the thirdphotoacoustic image and the ultrasound image may be generated in oneoperation mode. In this case, the image output means 26 may function asimage combination means for combining at least two of the firstphotoacoustic image, the second photoacoustic image, the thirdphotoacoustic image, and the ultrasound image. For example, the imageoutput means 26 may combine the first photoacoustic image and theultrasound image and display a composite image on the image displaymeans 16. Alternatively, the image output means 26 may combine thesecond photoacoustic image and the ultrasound image and display acomposite image on the image display means 16. The image output means 26may combine the third photoacoustic image and the ultrasound image anddisplay a composite image on the image display means 16. In addition,the image output means 26 may combine the first photoacoustic image, thesecond photoacoustic image, and the ultrasound image and display acomposite image on the image display means 16.

In this embodiment, the light with the first wavelength emitted from thefirst light source 13 is emitted to the light absorption member 51through the optical fiber 17 and the optical fiber 153 and the lightwith the second wavelength emitted from the second light source 14 isemitted to the light absorption member 51 through the optical fiber 18and the optical fiber 154. In a case in which the light absorptionmember 51 is irradiated with the light with the first wavelength, thelight absorption member 51 generates photoacoustic waves and the firstphotoacoustic image is generated on the basis of the detection signal ofthe photoacoustic waves. The first photoacoustic image includes thepositional information of the leading end of the puncture needle 15. Incontrast, in a case in which the light absorption member 51 isirradiated with the light with the second wavelength, the lightabsorption member 51 transmits the light with the second wavelength andthe light with the second wavelength is emitted from the leading end ofthe puncture needle 15 to the subject. In a case in which a lightabsorber is present in the part irradiated with the light with thesecond wavelength in the subject, photoacoustic waves are generated fromthe light absorber and the second photoacoustic image is generated onthe basis of the detection signal of the photoacoustic waves. The secondphotoacoustic image includes surrounding environment information.

In this embodiment, the light absorption member 51 that absorbs lightwith the first wavelength, generates photoacoustic waves, and transmitslight with the second wavelength without absorbing the light with thesecond wavelength is used. As such, the light absorption member 51 isused and is selectively irradiated with the light with the firstwavelength and the light with the second wavelength. Therefore, it ispossible to separately acquire both the positional information and thesurrounding environment information of the tip of the needle, using onepuncture needle 15. In a case in which a wavelength that is absorbed bya material in the part to be needled to generate photoacoustic waves isselected as the second wavelength, it is possible to determine whetherthe puncture needle 15 has been inserted into the part to be needled,using the second photoacoustic image. In this embodiment, in thepuncture needle 15, the optical fiber 153 is used to guide light withthe first wavelength and the optical fiber 154 is used to guide lightwith the second wavelength. Since the light with the first wavelengthand the light with the second wavelength are guided by the individualoptical fibers, it is possible to irradiate the light absorption member51 with the light with the first wavelength and the light with thesecond wavelength at the same time. In this case, it is possible toacquire the positional information and the surrounding environmentinformation of the tip of the needle at the same time.

Here, in JP2013-13713A, it is difficult to separate the photoacousticwaves generated by the absorption of light emitted from the lightemitting unit by a light absorber which is present in front of theneedle in the needling direction in the subject from the photoacousticwaves generated by the absorption of light emitted from the lightemitting unit by, for example, metal forming the puncture needle mainbody. Therefore, two bright points are mixed in the photoacoustic image.In some cases, since the intensity of the detected photoacoustic wavesis sequentially changed by the movement of the body or the movement ofthe probe, a bright point blinks in the photoacoustic image. InJP2013-13713A, in a case in which a reduction in the brightness of thebright point occurs in the photoacoustic image, the operator needs toperform, for example, an operation of changing the position or angle ofthe ultrasound probe to reconfirm the position or angle of the probe atwhich the brightness is the maximum. That is, JP2013-13713A has theproblem that the operator needs to perform an unnecessary operation.However, in this embodiment, in a case in which light is not emittedfrom the first light source 13 and the second light source 14 at thesame time, the positional information and the surrounding environmentinformation are separated from each other. Therefore, theabove-mentioned problems do not occur. In addition, in this embodiment,in a case in which light with the first wavelength and light with thesecond wavelength are emitted to the light absorption member 51 toacquire the positional information and the surrounding environmentinformation of the tip of the needle at the same time, the positionalinformation of the tip of the needle is acquired on the basis of thephotoacoustic waves generated from the light absorption member 51.Therefore, the positional information of the tip of the needle can bemore clearly acquired than that in JP2013-13713A in which the lightabsorption member 51 is not provided.

Next, a second embodiment of the invention will be described. Thisembodiment differs from the first embodiment in that the puncture needle15 further includes a phosphor. The phosphor is provided at the positionthat is irradiated with light emitted from the second light emittingportion 154 a (see FIG. 2) and converts light with the second wavelengthemitted from the second light emitting portion 154 a into light with athird wavelength. The third wavelength is different from the firstwavelength and the second wavelength. In this embodiment, in a case inwhich the second light source 14 emits light with the second wavelength,the subject is not irradiated with the light with the second wavelength,but is irradiated with the light with the third wavelength. The otherconfigurations may be the same as those in the first embodiment.

It is preferable that the phosphor emits light, for example, in ananosecond order. For example, a quantum dot or an organic phosphor(organic pigment) is used as the phosphor. It is preferable that thequantum dot is a PbS-based quantum dot. For example, a quantum dotmanufactured by Evident Technologies Inc. is used. The phosphor is mixedwith, for example, the light absorption member 51. Specifically, a lightabsorber that absorbs light with the first wavelength and transmitslight with the second wavelength and the phosphor are mixed with a resinsuch as an epoxy resin. Alternatively, the first light emitting portion153 a and the second light emitting portion 154 a may be covered withthe resin having the phosphor mixed therewith and each resin having thephosphor mixed therewith may be covered with the resin having the lightabsorber mixed therewith. On the contrary, the first light emittingportion 153 a and the second light emitting portion 154 a may be coveredwith the resin having the light absorber mixed therewith and then may becovered with the resin having the phosphor mixed therewith.

The phosphor mixed with the light absorption member 51 varies dependingon the puncture needle 15. For example, in a case in which there are aplurality of puncture needles 15, the wavelength of light emitted fromthe second light source 14 may be maintained to be the second wavelengthand the wavelength of fluorescent light emitted from the phosphor mayvary depending on the puncture needles 15. For example, the punctureneedle 15 for blood includes a phosphor that converts light with thesecond wavelength into light with a wavelength of 530 nm. In contrast,the puncture needle 15 for a nerve includes a phosphor that convertslight with the second wavelength into light with a wavelength of 1210nm. In a case in which the part to be needled is a blood vessel, thepuncture needle 15 for blood is used. In a case in which the part to beneedled is a nerve, the puncture needle for a nerve is used. In thisway, it is possible to select the target of which the surroundingenvironment information is to be evaluated, without changing thewavelength of light emitted from the second light source 14.

FIG. 10 illustrates the absorbance-wavelength characteristics of thephosphor. The horizontal axis indicates a wavelength and the verticalaxis indicates absorbance. FIG. 10 illustrates the absorbance-wavelengthcharacteristics of three PbS-based phosphors (quantum dots) representedby graphs (a) to (c). As can be seen from FIG. 10, these phosphors havehigh absorbance in the wavelength range of about 400 nm to 500 nm.Therefore, it is preferable that a light source which emits light with awavelength of 400 nm to 500 nm is used as the second light source 14. Ina case in which the first wavelength is 905 nm, the phosphorsrepresented by the graphs (b) and (c) absorb a certain amount of lightand generate photoacoustic waves. However, the intensity of thegenerated photoacoustic waves is sufficiently lower than that of thephotoacoustic waves generated from the light absorber of the lightabsorption member 51 and is as low as the level of noise, which causesno problem.

FIG. 11 illustrates the fluorescent emission intensity-wavelengthcharacteristics of the phosphor. The horizontal axis indicates awavelength and the vertical axis indicates emission intensity. FIG. 11illustrates the emission intensity-wavelength characteristics of threePbS-based phosphors (quantum dots) represented by graphs (a) to (c). Thephosphor represented by the graph (a) generates fluorescent light with awavelength of about 800 nm, using light with the second wavelength asexcitation light. The phosphor represented by the graph (b) generatesfluorescent light with a wavelength of about 1100 nm, using light withthe second wavelength as excitation light. The phosphor represented bythe graph (c) generates fluorescent light with a wavelength of about1500 nm, using light with the second wavelength as excitation light. Assuch, it is possible to generate fluorescent light components withdifferent wavelengths according to the phosphor used, while maintainingthe second wavelength.

In this embodiment, the puncture needle 15 includes the phosphor thatconverts light with the second wavelength into light with the thirdwavelength. In this case, the photoacoustic waves generated by theemission of the light with the third wavelength are detected and thesecond photoacoustic image is generated on the basis of the detectionsignal of the photoacoustic waves. In this way, it is possible toevaluate the surrounding environment of the leading end of the punctureneedle 15. In this embodiment, the phosphor used is changed to changethe wavelength of fluorescent light. Therefore, even in a case in whichthere are a plurality of evaluation targets, it is not necessary toprepare light sources that emit light components with a plurality ofwavelengths. As a result, it is possible to prevent an increase in theoverall cost of the apparatus. The other effects are the same as thosein the first embodiment.

Next, a third embodiment of the invention will be described. Thisembodiment differs from the first and second embodiments in that thepuncture needle 15 includes an outer needle and an inner needle. Theother configurations may be the same as those in the first embodiment orthe second embodiment.

FIG. 12 is a cross-sectional view illustrating a puncture needle 15 aaccording to this embodiment. In FIG. 12, the optical fiber 154 (seeFIG. 2) is not illustrated. A puncture needle main body 151 forming theouter needle has an opening at an acute leading end and has an innercavity. An inner needle 152 has substantially the same outside diameteras the inner cavity of the puncture needle main body 151 and isconfigured so as to be inserted into or removed from the hollow punctureneedle main body 151. The inner needle 152 is inserted into the innercavity of the puncture needle main body 151 from the base end side ofthe puncture needle main body 151 to seal at least a portion of theinner cavity of the puncture needle main body 151 to the extent that,for example, a section of the living body is prevented from beinginserted into the inner cavity. A protruding portion for connectionposition adjustment is provided in a base end portion of the innerneedle 152. A groove into which the protruding portion provided in thebase end portion of the inner needle 152 is fitted is provided in a baseend portion of the puncture needle main body 151. In a case in which theinner needle 152 is set in the puncture needle main body 151, theprotrusion portion provided in the base end portion of the inner needle152 and the groove provided in the base end portion of the punctureneedle main body 151 are positioned and the base end portion of theinner needle 152 is fitted to the base end portion of the punctureneedle main body 151.

The inner needle 152 includes the optical fiber 153, the optical fiber154 (not illustrated in FIG. 12), the light absorption member 51, a tube158, and a transparent resin 159. The tube 158 is, for example, a hollowtube made of polyimide. The tube 158 may be a metal tube made of, forexample, stainless steel. The outside diameter of the tube 158 isslightly less than the diameter of the inner cavity of the punctureneedle main body 151. The transparent resin 159 is provided in the tube158. For example, an epoxy resin (adhesive) is used as the transparentresin 159. The tube 158 and the transparent resin 159 are acute,similarly to the acute leading end of the puncture needle. Aphotocurable resin, a thermosetting resin, or a room-temperature-curableresin may be used as the transparent resin 159.

The optical fiber 153 and the optical fiber 154 are covered with thetransparent resin 159 in the tube 158. The light absorption member 51 isprovided at the leading ends of the optical fiber 153 and the opticalfiber 154. The light absorption member 51 is irradiated with lightemitted from the first light emitting portion 153 a and the second lightemitting portion 154 a. The light absorption member 51 may furtherinclude the phosphor described in the second embodiment. In a case inwhich the first light source 13 (see FIG. 1) emits light, the lightabsorption member 51 absorbs the emitted light with the first wavelengthand photoacoustic waves are generated at the leading end of the punctureneedle.

An operator, such as a doctor, inserts the puncture needle 15 a into thesubject, with the inner needle 152 set in the puncture needle main body151. Since the inner cavity of the puncture needle main body 151 isclosed by the inner needle 152, it is possible to prevent a piece offlesh from getting into the needle while the needle is being insertedand thus to prevent the needling sense of the operator from beinghindered. In addition, it is possible to prevent the inflow of waterfrom the part to be needled to the inner cavity of the puncture needlemain body 151. After inserting the needle into the subject, the operatorreleases the connection between the base end portion of the inner needle152 and the base end portion of the puncture needle main body 151 andtakes the inner needle 152 out of the puncture needle main body 151.After taking the inner needle 152 out of the puncture needle main body151, the operator can attach, for example, a syringe to the base endportion of the puncture needle main body 151 and inject a medicine suchas an anesthetic.

In addition, the transparent resin 159 may close at least a leading endportion of the tube 158 and does not necessarily close the entire insideof the tube 158. FIG. 13 is a cross-sectional view illustrating thevicinity of the leading end of a puncture needle according to amodification example. In a puncture needle 15 b, a transparent resin 159covers the light absorption member 51 covering the light emittingportion 153 a of the optical fiber 153 and the light emitting portion154 a of the optical fiber 154 (not illustrated in FIG. 13) and (theleading end portions of) the optical fibers 153 and 154 and the lightabsorption member 51 are fixed to the inner wall of the tube 158 by thetransparent resin 159. In addition, the transparent resin 159 closes anopening provided in the leading end portion of the tube 158. In a casein which this configuration is used, it is also possible to prevent theinflow of, for example, water into the inner needle 152.

The optical fiber 153 and the optical fiber 154 do not need to be fixedto the inner wall of the tube 158 by the transparent resin 159 and maybe fixed to the inner cavity of the tube 158 by the light absorptionmember 51. The leading end portion of the tube 158 may be closed by thelight absorption member 51. In this case, the transparent resin 159 maybe omitted. In addition, instead of the configuration in which theoptical fiber 153 and the optical fiber 154 are covered with thetransparent resin 159, the optical fiber 153 and the optical fiber 154may be covered with a resin with which at least one of the lightabsorber described in the first embodiment or the phosphor described inthe second embodiment is mixed.

In this embodiment, the puncture needle 15 b includes the inner needle152 provided in the inner cavity of the puncture needle main body 151.The inner needle 152 closes the inner cavity of the puncture needle mainbody 151 while the puncture needle 15 b is being inserted. Therefore, itis possible to prevent the needling sense of the operator from beinghindered and to prevent the inflow of water from the part to be needledto the inner cavity of the puncture needle main body 151. The othereffects are the same as those in the first embodiment or the secondembodiment.

In the above-described embodiments, the puncture needle 15 is consideredas an insert. However, the invention is not limited thereto. The insertmay be a radio frequency ablation needle including an electrode that isused for radio frequency ablation, a catheter that is inserted into ablood vessel, or a guide wire for a catheter that is inserted into ablood vessel. Alternatively, the insert may be an optical fiber forlaser treatment.

In the above-described embodiments, a needle having an opening at theleading end is assumed as the needle. However, the opening is notnecessarily provided at the leading end of the needle. The needle is notlimited to an injection needle and may be a biopsy needle used forbiopsy. That is, the needle may be a biopsy needle that is inserted intoan inspection target of the living body and extracts the tissues of abiopsy site of the inspection target. In this case, photoacoustic wavesmay be generated from an extraction portion (intake port) for suckingand extracting the tissues of the biopsy site. In addition, the needlemay be used as a guiding needle that is used for insertion into a deeppart, such as a part under the skin or an organ inside the abdomen.

The puncture needle 15 is not limited to the needle that is insertedfrom the outside of the subject into the subject through the skin andmay be a needle for ultrasound endoscopy. The optical fibers 153 and 154and the light absorption member 51 may be provided in the needle forultrasound endoscopy. The light absorption member 51 provided in theleading end portion of the needle may be irradiated with at least one oflight with the first wavelength or light with the second wavelength.Then, photoacoustic waves may be detected and a photoacoustic image (thefirst photoacoustic image, the second photoacoustic image, or the thirdphotoacoustic image) may be generated. In this case, it is possible toperform needling while observing the first photoacoustic image andchecking the position of the leading end portion of the needle forultrasound endoscopy. In addition, it is possible to determine whetheran evaluation target material is present in the vicinity of the needle,using the second photoacoustic image. In a case in which the thirdphotoacoustic image is generated, it is possible to determine theposition of the tip of the needle and to determine whether an evaluationtarget material is present. The first photoacoustic waves generated fromthe leading end portion of the needle for ultrasound endoscopy and thesecond photoacoustic waves generated from the vicinity of the leadingend portion may be detected by a probe for body surface or a probe thatis incorporated into an endoscope.

The optical fiber 153 and the optical fiber 154 in the puncture needle15 have any positional relationship therebetween. FIG. 14 illustrates apuncture needle according to another modification example. In thismodification example, similarly to the puncture needle illustrated inFIG. 2, the optical fiber 153 and the optical fiber 154 are disposed soas to be adjacent to each other in the puncture needle 15 c. In FIG. 14,particularly, of two optical fibers, the optical fiber 153 that guideslight with the first wavelength is disposed at the center of a punctureneedle 15 c in a width direction. Here, the position of the center ofthe puncture needle in the width direction means the position of thecenter in the width direction in a case in which the needle is viewedfrom the upper side with a sharp portion of the leading end of theneedle facing down or up. As illustrated in FIG. 14, in a case in whichthe first light emitting portion 153 a provided at the leading end ofthe optical fiber 153 is disposed at the center of (the opening of) thepuncture needle 15 in the width direction, it is possible to generatethe first photoacoustic waves at the center of the puncture needle 15 cin the width direction.

The optical fiber 153 and the optical fiber 154 are not necessarilydisposed so as to be adjacent to each other. FIG. 15 illustrates apuncture needle according to still another modification example. In apuncture needle 15 d according to this modification example, the opticalfiber 153 and the optical fiber 154 are disposed with a gaptherebetween. In this case, instead of the configuration in which onelight absorption member 51 covers the first light emitting portion 153 aand the second light emitting portion 154 a, the first light emittingportion 153 a and the second light emitting portion 154 a may beseparately covered with the light absorption member 51, as illustratedin FIG. 15. In this case, it is preferable that the amount of lightabsorption member 51 covering the first light emitting portion 153 a ismore than the amount of light absorption member 51 covering the secondlight emitting portion 154 a in order to generate the firstphotoacoustic waves with sufficiently high intensity. The second lightemitting portion 154 a may be covered with a transparent resin insteadof the light absorption member 51.

The optical fiber 153 and the optical fiber 154 are not necessarilyarranged in the width direction of the puncture needle. FIG. 16illustrates a puncture needle according to yet another modificationexample. In a puncture needle 15 e according to this modificationexample, the optical fiber 153 is provided on an inner wall on the sidewhere the puncture needle main body 151 is the longest and the leadingend is sharp. In contrast, the optical fiber 154 is provided on an innerwall (a position that is rotated 180° about the axial direction of thepuncture needle) opposite to the inner wall. In this modificationexample, the first light emitting portion 153 a provided at the leadingend of the optical fiber 153 and the second light emitting portion 154 aprovided at the leading end of the optical fiber 154 are separated fromeach other. In this modification example, the second light emittingportion 154 a may be covered with a transparent resin as described inthe modification example illustrated in FIG. 15.

The invention has been described above on the basis of the preferredembodiments. However, the photoacoustic image generation apparatus andthe insert according to the invention are not limited to theabove-described embodiments. Various modifications and changes of theconfigurations according to the above-described embodiments are alsoincluded in the scope of the invention.

In the above description, it is preferable that an amount of lightabsorption member covering the first light emitting portion is more thanan amount of light absorption member covering the second light emittingportion.

The light absorption member may include a light absorber that absorbsthe light with the first wavelength and transmits the light with thesecond wavelength and a resin including the light absorber.

The insert according to the invention may have an inner cavity. Thelight absorption member may function as a fixing member that fixes thelight guide members to an inner wall of the inner cavity of the insert.

The insert according to the invention may further includes a transparentresin that transmits at least the light with the second wavelength. Inthis case, the light absorption member may be covered with thetransparent resin.

The insert according to the invention may have an inner cavity. Thefirst light guide member, the second light guide member, and the lightabsorption member may be fixed to an inner wall of the inner cavity ofthe insert by the transparent resin.

The insert according to the invention may be a puncture needle having aninner cavity. In this case, the puncture needle may further include ahollow tube in which the first light guide member and the second lightguide member are accommodated.

In the invention, the puncture needle may include an inner needle and anouter needle. In this case, the inner needle may include the hollowtube. The inner needle may seal at least a portion of the inner cavity.

In the invention, the light absorption member may function as a fixingmember that fixes the light guide members to an inner wall of the hollowtube.

The insert according to the invention may further include a transparentresin that transmits at least the light with the second wavelength. Thefirst light guide member, the second light guide member, and the lightabsorption member may be fixed to an inner wall of the hollow tube bythe transparent resin.

In the invention, it is preferable that the first light emitting portionis provided at a center of the insert in a width direction.

The insert according to the invention may further include a phosphorthat converts the light with the second wavelength emitted from thesecond light emitting portion into light with a third wavelengthdifferent from the first wavelength and the second wavelength.

Preferably, the insert according to the invention further includes: anoptical connector that detachably connects the first light guide memberand an optical fiber which guides the light with the first wavelengthemitted from a first light source; and an optical connector thatdetachably connects the second light guide member and an optical fiberwhich guides the light with the second wavelength emitted from a secondlight source.

In the above description, the second photoacoustic waves may begenerated by the absorption of the light with the second wavelengthtransmitted through the light absorption member by the subject.

The insert may further include a phosphor that converts the light withthe second wavelength emitted from the second light emitting portioninto light with a third wavelength different from the first wavelengthand the second wavelength. In this case, the second photoacoustic wavesmay be generated by the absorption of the light with the thirdwavelength emitted from the phosphor by the subject.

In the photoacoustic image generation apparatus according to theinvention, the acoustic wave detection unit may further detect reflectedacoustic waves with respect to acoustic waves transmitted to thesubject. In this case, preferably, the photoacoustic image generationapparatus further includes reflected acoustic image generation unit forgenerating a reflected acoustic image on the basis of the reflectedacoustic waves.

The photoacoustic image generation apparatus according to the inventionmay further include image combination unit for combining at least one ofthe first photoacoustic image, the second photoacoustic image, or thethird photoacoustic image and the reflected acoustic image.

The photoacoustic image generation apparatus and the insert according tothe invention can acquire both the positional information and thesurrounding environment information of the insert.

What is claimed is:
 1. An insert that is at least partially insertedinto a subject, comprising: a first light guide member that guides lightwith a first wavelength; a first light emitting portion from which thelight guided by the first light guide member is emitted; a second lightguide member that guides light with a second wavelength different fromthe first wavelength; a second light emitting portion from which thelight guided by the second light guide member is emitted; and a lightabsorption member that at least partially covers both the first lightemitting portion and the second light emitting portion, absorbs thelight with the first wavelength emitted from the first light emittingportion to generate photoacoustic waves, and transmits the light withthe second wavelength emitted from the second light emitting portion,wherein an amount of light absorption member covering the first lightemitting portion is more than an amount of light absorption membercovering the second light emitting portion.
 2. The insert according toclaim 1, wherein the light absorption member includes a light absorberthat absorbs the light with the first wavelength and transmits the lightwith the second wavelength and a resin including the light absorber. 3.The insert according to claim 1, wherein the insert has an inner cavity,and the light absorption member functions as a fixing member that fixesthe first light guide member and the second light guide member to aninner wall of the inner cavity.
 4. The insert according to claim 1,further comprising: a transparent resin that transmits at least thelight with the second wavelength, wherein the light absorption member iscovered with the transparent resin.
 5. The insert according to claim 4,wherein the insert has an inner cavity, and the first light guidemember, the second light guide member, and the light absorption memberare fixed to an inner wall of the inner cavity by the transparent resin.6. The insert according to claim 1, wherein the insert is a punctureneedle having an inner cavity, and the insert further includes a hollowtube in which the first light guide member and the second light guidemember are accommodated.
 7. The insert according to claim 6, wherein thepuncture needle includes an inner needle and an outer needle, the innerneedle includes the hollow tube, and the inner needle seals at least aportion of the inner cavity.
 8. The insert according to claim 6, whereinthe light absorption member functions as a fixing member that fixes thefirst light guide member and the second light guide member to an innerwall of the hollow tube.
 9. The insert according to claim 6, furthercomprising: a transparent resin that transmits at least the light withthe second wavelength, wherein the first light guide member, the secondlight guide member, and the light absorption member are fixed to aninner wall of the hollow tube by the transparent resin.
 10. The insertaccording to claim 1, wherein the first light emitting portion isprovided at a center of the insert in a width direction.
 11. The insertaccording to claim 1, further comprising: an optical connector thatdetachably connects the first light guide member and an optical fiberwhich guides the light with the first wavelength emitted from a firstlight source; and an optical connector that detachably connects thesecond light guide member and an optical fiber which guides the lightwith the second wavelength emitted from a second light source.
 12. Aninsert that is at least partially inserted into a subject, comprising: afirst light guide member that guides light with a first wavelength; afirst light emitting portion from which the light guided by the firstlight guide member is emitted; a second light guide member that guideslight with a second wavelength different from the first wavelength; asecond light emitting portion from which the light guided by the secondlight guide member is emitted; a light absorption member that at leastpartially covers both the first light emitting portion and the secondlight emitting portion, absorbs the light with the first wavelengthemitted from the first light emitting portion to generate photoacousticwaves, and transmits the light with the second wavelength emitted fromthe second light emitting portion; and a phosphor that converts thelight with the second wavelength emitted from the second light emittingportion into light with a third wavelength different from the firstwavelength and the second wavelength.
 13. The insert according to claim12, wherein the light absorption member includes a light absorber thatabsorbs the light with the first wavelength and transmits the light withthe second wavelength and a resin including the light absorber.
 14. Theinsert according to claim 12, wherein the insert has an inner cavity,and the light absorption member functions as a fixing member that fixesthe first light guide member and the second light guide member to aninner wall of the inner cavity.
 15. The insert according to claim 12,further comprising: a transparent resin that transmits at least thelight with the second wavelength, wherein the light absorption member iscovered with the transparent resin.
 16. The insert according to claim12, wherein the insert has an inner cavity, and the first light guidemember, the second light guide member, and the light absorption memberare fixed to an inner wall of the inner cavity by the transparent resin.17. The insert according to claim 12, wherein the insert is a punctureneedle having an inner cavity, and the insert further includes a hollowtube in which the first light guide member and the second light guidemember are accommodated.
 18. The insert according to claim 12, whereinthe puncture needle includes an inner needle and an outer needle, theinner needle includes the hollow tube, and the inner needle seals atleast a portion of the inner cavity.
 19. The insert according to claim12, wherein the light absorption member functions as a fixing memberthat fixes the first light guide member and the second light guidemember to an inner wall of the hollow tube.
 20. The insert according toclaim 12, further comprising: a transparent resin that transmits atleast the light with the second wavelength, wherein the first lightguide member, the second light guide member, and the light absorptionmember are fixed to an inner wall of the hollow tube by the transparentresin.
 21. The insert according to claim 12, wherein the first lightemitting portion is provided at a center of the insert in a widthdirection.
 22. The insert according to claim 12, further comprising: anoptical connector that detachably connects the first light guide memberand an optical fiber which guides the light with the first wavelengthemitted from a first light source; and an optical connector thatdetachably connects the second light guide member and an optical fiberwhich guides the light with the second wavelength emitted from a secondlight source.
 23. A photoacoustic image generation apparatus comprising:a first light source that emits light with a first wavelength; a secondlight source that emits light with a second wavelength different fromthe first wavelength; an insert that is at least partially inserted intoa subject and comprises a first light guide member which guides thelight with the first wavelength, a first light emitting portion fromwhich the light guided by the first light guide member is emitted, asecond light guide member which guides the light with the secondwavelength, a second light emitting portion from which the light guidedby the second light guide member is emitted, and a light absorptionmember which at least partially covers both the first light emittingportion and the second light emitting portion, absorbs the light withthe first wavelength emitted from the first light emitting portion togenerate photoacoustic waves, and transmits the light with the secondwavelength emitted from the second light emitting portion; a probeconfigured to detect first photoacoustic waves which are generated bythe absorption of the light with the first wavelength by the lightabsorption member and second photoacoustic waves which are generated inthe subject due to the light emitted from the second light emittingportion; and a processor configured to generate a first photoacousticimage on the basis of the first photoacoustic waves and a secondphotoacoustic image on the basis of the second photoacoustic waves. 24.The photoacoustic image generation apparatus according to claim 23,wherein the second photoacoustic waves are generated by the absorptionof the light with the second wavelength transmitted through the lightabsorption member by the subject.
 25. The photoacoustic image generationapparatus according to claim 23, wherein the insert further includes aphosphor that converts the light with the second wavelength emitted fromthe second light emitting portion into light with a third wavelengthdifferent from the first wavelength and the second wavelength, and thesecond photoacoustic waves are generated by the absorption of the lightwith the third wavelength emitted from the phosphor by the subject. 26.The photoacoustic image generation apparatus according to claim 23,wherein the probe is further configured to detect reflected acousticwaves with respect to acoustic waves transmitted to the subject, and theprocessor is further configured to generate a reflected acoustic imageon the basis of the reflected acoustic waves.
 27. The photoacousticimage generation apparatus according to claim 26, wherein the processoris further configured to combine at least one of the first photoacousticimage or the second photoacoustic image, and the reflected acousticimage.
 28. The photoacoustic image generation apparatus according toclaim 23, wherein the processor is further configured to generate athird photoacoustic image on the basis of both the first photoacousticwaves and the second photoacoustic waves.